Do you know in which galaxy we live? You all might be knowing about it. It is your Milky Way Galaxy. Have you ever wondered what our Milky Way Galaxy looks like, what part of the universe is the Milky Way, what are its parts? etc. You might have come across these questions so, let's find the answers...
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| Edwin Hubble |
Until 1920 most astronomers believed that our Milky Way galaxy contained all the stars in the universe. But observation by Edwin Hubble proved that many stars are outside our galaxy which we can't see, and he also showed that Milky Way is just one of the galaxies in the universe.
Formation of the Milky Way Galaxy
After the formation of the universe, hydrogen and helium were roaming all around, it also contained dust and dark matter. As time passed many changes were occurring in the universe, one of these changes was the formation of the stars from the gases present. After 100 billion years of the formation of the universe, because of gravity, these stars, dust, and dark matter started coming near and forming star clusters. As time passed all these stars merged to form a disc-like shape which was the galaxies. Many small galaxies began to merge, and our galaxy was growing in size. The early Milky Way galaxy was spherical but, after some years our galaxy gained so much mass that it started spinning quickly. It converted into a spiral galaxy from a spherical galaxy. Our galaxy is one of the first galaxies in the universe.
Structure, Dimension, and Characteristics
As Milky Way is a spiral galaxy, it has arms. Milky Way Galaxy has six spiral arms:
- Perseus Arm
- Norma Arm
- Outer Arm
- Scutum - Centaurus Arm
- Carina - Sagittarius Arm
- Orion - Cygnus Arm
Mainly all the galaxies have a central black hole, like that the Milky Way has a central black hole named Sagittarius A*. As you may be knowing that it is not possible to see black holes directly so we do not know much about them, however, astronomers say that Sagittarius A* is a supermassive black hole that has a diameter of 44,000,000 km. Sagittarius A* is present in the Sagittarius constellation and it has got its name from there. Please note that the Sagittarius arm and Sagittarius constellation are different. Sagittarius arm is an arm of our galaxy while the Sagittarius constellation is a constellation.
- Number of stars: 100-400 billion
- Age: 13.61 billion years
- Diameter: 105,700 light-years
- Mass: 1.2-1.9 solar masses
- Number of Planets: 100 billion
- Speed of Galaxy in-universe: 210 km/s
Our Solar System or you can say our Earth lies in Orion - Cygnus Arm of the Milky Way Galaxy. Our solar system is 27,000 light-years away from the central bulge of the Milky Way. Our Solar System is moving at a speed of 230 km/s around the galaxy and it takes 250 million years to complete an orbit.
